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Does shaving really make your hair thicker?

January 26, 2020 / Duncan Fisher
No, though it might look like it does

Many is the high school boy who shaves that first peach-fuzz moustache, probably because his dad told him to, and finds to his delight that manly stubble grows in its place.

Many are the teenage girls who tell their friends, in horror, the very same story about their legs.

Everyone in high school knows, or seems to know, that shaving makes your hair come back thicker all of a sudden. And it’s denser. And it also grows faster. Somehow, goes the lore, your follicles run berserk the minute you put a potion on your skin and give it that first scrape.

High school kids think this because they see it. Their hair does bristle up about the time they start shaving. It gets darker, too, so the change can look pretty dramatic.

They’re not wrong about what they see, either. But they are wrong about what they infer.

It’s adolescence that makes you hairier. Shaving does not.

If it did, we could all grow hairy chests if we wanted, simply by shaving our mighty pectorals, and we could forever prevent baldness, too, the very same way.

That shaving thing is a myth

Shaving changes absolutely nothing about the physiology of hair.

We’re sure about this, because it’s been very well examined in medical literature (you’ll be glad to know). The most famous study was in 1970, when the Journal of Investigative Dermatology published the results of a controlled trial in which a cohort of medically sound young men were each asked to shave one leg (leaving the other for comparison) and present themselves for dermatological assessment.

All the metrics showed that the men’s hair production didn’t change at all.

The team observed that there is no biological basis for thinking that shaving should cause physiological changes in women’s skin, either.

Shaving should therefore make no one hairy.

And that’s been the consensus with all subsequent studies. Any evidence to the contrary is only anecdotal, however convincing it may seem – and it may seem very convincing. Uncut hair, as any beautician will tell you, tapers at the end. Cut straight across, it does look suddenly coarse. But cutting a hair shaft still doesn’t change a thing in the biochemistry of hair formation down in the follicle, or change follicle shape, or increase the number of follicles, or do anything else.

The same goes for waxing, by the way. There’s no evidence that yanking a hair out of a follicle changes anything about that follicle or what goes on within it. We could see the changes if it did. A simple biopsy would reveal all. If waxing seems to increase hair production, it’s because all the hair shafts begin regrowing at the same time. It can look for all the world like there’s more hair. But there isn’t. We can measure that. We're sure.

What if you really do get hairier?

Sometimes there are changes, that are undeniable. Sometimes there’s suddenly hair where there wasn’t hair before.

That's almost always about hormones.

In women, who are the people who care most about it, this hormone-driven ‘hirsutism’ can have any of a number of root causes. It can be a function of dramatic weight gain. It could be secondary to a condition called ‘polycystic ovarian syndrome,’ or another, known as ‘adrenal hyperplasia.’ Very occasionally, there can be tumors in ovaries or adrenal glands that cause problems. More commonly, medications are the culprit. These are typically the ones prescribed as part of hormone treatment.

If you really do have unexpected hair growth, your dermatologist will be able to tell what’s going on. If it turns out to be a complex hormone problem, you will probably be referred to an endocrinologist.

Nobody will tell you to stop shaving.

Shave away, and don’t worry

That's the punchline. Whatever they may have told you in high school, shaving is just not going to make your hair grow more. There is no known mechanism of action by which that could happen, and there’s no evidence at all that it ever did happen.

Questions about your skin? Ask our dermatologists online for $35.